Breaking up with a narcissist

I need help so I’m been with this narcissist for so long for almost 10 years on and off. Today I build the courage to let go and say no more to the mental abuse I experienced later on in the relationship. It started off well I feel like he was the one I couldn’t let go. I feel like I was inside a hole and I felt like I was never gonna find someone like him. But my mental help was in jeopardy my mental health was falling apart. Then I realize that my mental health and myself meant more than him. It hasn’t been easy but deep inside I knew I had to do what I needed to do and that was to let him go.